1. Field of the Invention
The present invention relates to a focal controller applied to a camera such as a video camera, an electronic still camera, etc. having a solid-state image sensor.
2. Description of the Related Art
An automatic focusing system (a so-called mountaineering servo system) using a video signal as a focal evaluation value is generally adopted in a video camera, etc. However, in this system, a focusing motor is driven while the focal evaluation value is basically obtained every one field and is compared with a reference value. Accordingly, this system has a problem of increasing a focusing time.
Further, there is a case in which scatter in characteristic curve of an evaluation value relative to a brightness component is caused by a photographed subject, its condition, noises, etc. In this case, the focusing motor is driven at a high speed even near a focusing position. Therefore, an overrunning amount of the focusing lens with respect to the focusing position is large so that a pickup image becomes bad in appearance. Further, a focusing time of the focusing lens is increased in accordance with the overrunning amount.